Photolithography and electron beam lithography are known as methods for fabricating fine structures of several tens to several hundreds of nanometers, and have been applied to produce various semiconductor devices. Photolithography involves time-consuming steps for exposing a resist film surface to patterns of interconnections after they are contracted, and for developing them. Electron beam lithography directly draws images by electron beams, and hence takes much time to draw them on a number of substrates. For these reasons, the conventional lithography is difficult to realize a high through-put. On the other hand, nano-imprinting is proposed, e.g., by Non-patent Document 1, as a method for fabricating micro- or nano-structure at a high through-put. This method prepares a mold comprising an Si or metallic substrate on which a desired indentation/protrusion pattern is drawn, and presses the mold against a polymer film heated above its glass transition temperature to transfer the pattern image onto the film, which carries the reversed image. The compounds for the polymer film include thermoplastic ones, e.g., polymethyl methacrylate (PMMA), polycarbonate, polystyrene and cross-linked compound thereof; and thermosetting ones, e.g., polyimide. The nano-imprinting can produce structures with polymer pillars having a diameter of several tens to hundreds of nanometers, and those characterized by their cavity or groove structures. The substrate thus processed can possibly exhibit physically interesting characteristics, e.g., optical characteristics, and, at the same time, can find interesting applications as a substrate for supporting biomaterials, e.g., living body cells, proteins and DNAs.
(Non-patent Document 1) Journal of Vacuum Science and Technology, B14, 4129 (1996)